1. Field of the Invention
This invention relates to an acoustical barrier for reducing the transfer of sound through a panel member; and more specifically, to a wall-mounted acoustical barrier with a decoupler for separating the acoustical barrier from the panel to enhance the sound reducing properties of the acoustical barrier.
2. Description of Related Art
Acoustical barriers are commonly used in contemporary motor vehicles to reduce the engine and road noise. Most vehicles have a sheet metal barrier wall between the engine compartment and the passenger compartment, physically separating the engine compartment and the passenger compartment. Unfortunately, the metal barrier wall readily transmits sound from the engine compartment into the passenger compartment.
Previous acoustical barriers have been constructed to reduce or eliminate the sound transfer through the barrier wall. One of these prior acoustic barriers generally comprises a foam or other decoupling layer and a mass layer, both of which are sheets coextensive with the barrier wall. The foam layer and mass layer are bonded together and the acoustic barrier is mounted to the barrier wall so that the foam layer is positioned against the barrier wall within the passenger compartment. The foam layer serves to separate or decouple the mass layer from the barrier wall to minimize the direct transfer of sound vibrations through the mass layer.
In order to maximize sound decoupling, the decoupling layer should have a predetermined thickness. Also, the mass layer should present a smooth appearance in order to provide a surface on which carpets and other materials can be mounted within the vehicle passenger compartment. The barrier wall typically has multiple curves and indentations, resulting in uneven barrier wall surfaces, making it difficult to conform the decoupling layer to the barrier wall, while maintaining a smooth mass layer. Previous acoustic barriers have solved the problem of conforming the decoupling layer to the barrier wall while presenting a smooth exterior mass layer by making the decoupling layer of a thickness that is the sum of the maximum depth of the indentations plus a minimum desired decoupling layer thickness. Portions of the decoupling layer corresponding to the unrecessed areas of the barrier wall are compressed so that the one side of the decoupling layer conforms to the surface of the barrier wall, including portions protruding into the indentations, while the other side remains a smooth surface. The mass layer is then mounted to the smooth surface of the decoupling layer.
Although the previous solution is acceptable, excess decoupling material must be used and the decoupling layer compressing step is an extra process step, thereby increasing the cost of the decoupler. The present invention relates to an acoustical barrier that minimizes the amount of decoupling material in the decoupler and eliminates the decoupling layer compression step. The invention results in a novel solution to the physical and aesthetic problems associated with previous acoustic barriers, while substantially reducing the material and production costs.